Black Box Explains...4K

4K is a term to describe a maximum video resolution of 4096 x 2400 pixels. However, the most commonly used resolution is UHD (Ultra High Definition) at 3840 x 2160 pixels. This resolution basically allows for four full HD signals of 1920 x 1080 pixels to be displayed on a single screen. Unfortunately, the pure pixel count doesn't tell the complete the story. The following overview provides an examination of some key differences to provide users with a better understanding of potential requirements to help select suitable solutions.

Full 4K resolutions of 3840 x 2160 or higher over DVI dual link are possible, but only at less than 30 Hz due to bandwidth limitations. The bandwidth required for professional AV and PC environments can come to 4.95 Gbps (165 Mhz) for single link or 9.9 Gbps (2x 165 Mhz) for dual-link DVI.

The specifications vary based on the different HDMI versions. Up to HDMI 1.2 the specs more or less reflect those of DVI video. HDMI 1.3 and 1.4 exceed the dual-link DVI specs although it only uses a single link. HDMI 1.3/1.4 bandwidth is 10.2 Gbps (single link 140 Mhz).

Most HDMI 4K appliances and displays currently on the market are limited to 30 Hz. The recently released HDMI 2.0 standard increases bandwidth to 18 Gpbs (600 Mhz), effectively matching the bandwidth of DisplayPort for supporting 4K at up to 60 fps. The first HDMI 2.0 displays supporting this full specification are presently showing up on the market. HDMI is commonly used on almost all consumer and professional AV equipment.

DisplayPort 1.2
DisplayPort is a slightly different, micro packet-based, video standard supporting a maximum bandwidth of approximately 17 Gbits. This currently makes it the only suitable single-connect option for full UHD (3840 x 2160) at 60 fps.

DisplayPort is mainly used on PC graphic adapter cards. Note: all current graphics cards with
DisplayPort support the full DisplayPort 1.2a specification of 5.4 Gbps per lane and therefore only support 30 fps rather than 60 fps 4K resolutions.

Thunderbolt
Thunderbolt 1.0 is an Apple-only interface for multi-purpose use including video. Thunderbolt is compatible with DP 1.1 and capable of natively outputting DisplayPort signals. Thunderbolt 2.0 is needed to support 4K at 60Hz, and is compatible with DisplayPort 1.2.

Different ways of delivering 4K
Depending on the specifications of the equipment being used, a 4K signal may be delivered in the following ways:

Full spec 60 fps
•Display/projector with four single-link DVI interfaces and synchronized channels. Acts like a video wall in just a single large device.
•Display/projector with two dual-link DVI interfaces and synchronized channels. Acts like a video wall in just a single large device.
•Display/projector with either two dula-link DVI or HDMI 1.4 inputs. The term used to describe this method is Multiple Protocol Transport (MPT).
•Display with either DisplayPort, Thunderbolt, or upcoming HDMI 2.0 full spec interfaces.